In serial data transfer, synchronization for transfer must be established so that data is transferred between the receiving side and the transmitting side. For this reason, a quartz oscillator having high oscillation accuracy has been used, or a PLL (Phase-Locked Loop) or the like has been used to realize frame synchronization for the purpose of establishing the synchronization in data transfer with higher accuracy.
Because of the quartz oscillator and the PLL being expensive, however, it has been difficult to realize an inexpensive sensor device, actuator device, etc. which can realize the serial data transfer.
Accordingly, the inexpensive sensor device is mainly employed in the signal transfer using an analog voltage, and this type of signal transfer has limitations in transfer distance and transfer accuracy.
With that problem in mind, there is proposed a start-stop synchronization data transfer method for transferring serial data with an oscillator having low frequency accuracy, as disclosed in JP,A 2000-196700.
The disclosed start-stop synchronization data transfer method requires neither the expensive quartz oscillator nor the PLL.